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566 lines
21 KiB
Markdown
566 lines
21 KiB
Markdown
# 첫 번째 애플리케이션 튜토리얼(Hello Sky)
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첫 번째 온보드 애플리케이션을 만들고 실행하는 방법을 설명합니다.
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PX4에서 앱 개발에 필요한 기본 개념과 API를 설명합니다.
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:::info
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For simplicity, more advanced features like start/stop functionality and command-line arguments are omitted.
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These are covered in [Application/Module Template](../modules/module_template.md).
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:::
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## 준비 사항
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다음과 같은 것이 필요합니다.
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- [Gazebo Simulator](../sim_gazebo_gz/index.md) (or another [PX4 SITL Simulator](../simulation/index.md)) _or_ a [PX4-compatible flight controller](../flight_controller/index.md).
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- [PX4 Development Toolchain](../dev_setup/dev_env.md) for the desired target.
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- [Download the PX4 Source Code](../dev_setup/building_px4.md#download-the-px4-source-code) from Github
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The source code [PX4-Autopilot/src/examples/px4_simple_app](https://github.com/PX4/PX4-Autopilot/tree/main/src/examples/px4_simple_app) directory contains a completed version of this tutorial that you can review if you get stuck.
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:::tip
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Rename (or delete) the **px4_simple_app** directory.
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:::
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## 간단한 어플리케이션
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In this section we create a _minimal application_ that just prints out `Hello Sky!`.
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This consists of a single _C_ file and a _cmake_ definition (which tells the toolchain how to build the application).
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1. Create a new directory **PX4-Autopilot/src/examples/px4_simple_app**.
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2. Create a new C file in that directory named **px4_simple_app.c**:
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- 기본 헤더를 페이지 상단에 복사합니다.
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이것은 기여한 모든 파일에 첨부하여야 합니다.
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```c
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/****************************************************************************
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*
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* Copyright (c) 2012-2026 PX4 Development Team. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name PX4 nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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```
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- 기본 헤더 아래에 다음 코드를 복사합니다.
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Similar code should be present in all contributed files!
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```c
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/**
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* @file px4_simple_app.c
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* Minimal application example for PX4 autopilot
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*
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* @author Example User <mail@example.com>
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*/
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#include <px4_platform_common/log.h>
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__EXPORT int px4_simple_app_main(int argc, char *argv[]);
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int px4_simple_app_main(int argc, char *argv[])
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{
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PX4_INFO("Hello Sky!");
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return OK;
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}
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```
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:::tip
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The main function must be named `<module_name>_main` and exported from the module as shown.
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:::
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:::tip
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`PX4_INFO` is the equivalent of `printf` for the PX4 shell (included from **px4_platform_common/log.h**).
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There are different log levels: `PX4_INFO`, `PX4_WARN`, `PX4_ERR`, `PX4_DEBUG`.
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Warnings and errors are additionally added to the [ULog](../dev_log/ulog_file_format.md) and shown on [Flight Review](https://logs.px4.io/).
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:::
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3. Create and open a new _cmake_ definition file named **CMakeLists.txt**.
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아래 텍스트를 복사하십시오.
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```cmake
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############################################################################
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#
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# Copyright (c) 2015 PX4 Development Team. All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions
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# are met:
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#
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# 1. Redistributions of source code must retain the above copyright
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# notice, this list of conditions and the following disclaimer.
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# 2. Redistributions in binary form must reproduce the above copyright
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# notice, this list of conditions and the following disclaimer in
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# the documentation and/or other materials provided with the
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# distribution.
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# 3. Neither the name PX4 nor the names of its contributors may be
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# used to endorse or promote products derived from this software
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# without specific prior written permission.
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#
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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# COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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# OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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# POSSIBILITY OF SUCH DAMAGE.
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#
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############################################################################
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px4_add_module(
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MODULE examples__px4_simple_app
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MAIN px4_simple_app
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STACK_MAIN 2000
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SRCS
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px4_simple_app.c
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DEPENDS
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)
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```
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Note that in your own modules you'd use the current copyright year!
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We're using `2015` here to match the example.
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The `px4_add_module()` method builds a static library from a module description.
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- The `MODULE` block is the Firmware-unique name of the module (by convention the module name is prefixed by parent directories back to `src`).
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- The `MAIN` block lists the entry point of the module, which registers the command with NuttX so that it can be called from the PX4 shell or SITL console.
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:::tip
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The `px4_add_module()` format is documented in [PX4-Autopilot/cmake/px4_add_module.cmake](https://github.com/PX4/PX4-Autopilot/blob/main/cmake/px4_add_module.cmake). <!-- NEED px4_version -->
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:::
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::: info
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If you specify `DYNAMIC` as an option to `px4_add_module`, a _shared library_ is created instead of a static library on POSIX platforms (these can be loaded without having to recompile PX4, and shared to others as binaries rather than source code).
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Your app will not become a builtin command, but ends up in a separate file called `examples__px4_simple_app.px4mod`.
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You can then run your command by loading the file at runtime using the `dyn` command: `dyn ./examples__px4_simple_app.px4mod`
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:::
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4. Create and open a new _Kconfig_ definition file named **Kconfig** and define your symbol for naming (see [Kconfig naming convention](../hardware/porting_guide_config.md#px4-kconfig-symbol-naming-convention)).
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아래 텍스트를 복사하십시오.
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```txt
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menuconfig EXAMPLES_PX4_SIMPLE_APP
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bool "px4_simple_app"
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default n
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---help---
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Enable support for px4_simple_app
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```
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## 애플리케이션/펌웨어 빌드
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이제 어플리케이션 제작이 완료되었습니다.
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실행하려면 먼저 PX4의 일부로 빌드되었는지 확인합니다.
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Applications are added to the build/firmware in the appropriate board-level _px4board_ file for your target:
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- PX4 SITL (Simulator): [PX4-Autopilot/boards/px4/sitl/default.px4board](https://github.com/PX4/PX4-Autopilot/blob/main/boards/px4/sitl/default.px4board)
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- Pixhawk 6X (px4/fmu-v6x): [PX4-Autopilot/boards/px4/fmu-v6x/default.px4board](https://github.com/PX4/PX4-Autopilot/blob/main/boards/px4/fmu-v6x/default.px4board)
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- _px4board_ files for other boards can be found in [PX4-Autopilot/boards/](https://github.com/PX4/PX4-Autopilot/tree/main/boards)
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To enable the compilation of the application into the firmware add the corresponding Kconfig key `CONFIG_EXAMPLES_PX4_SIMPLE_APP=y` in the _px4board_ file or run [boardconfig](../hardware/porting_guide_config.md#px4-menuconfig-setup).
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For example, to edit the board config for FMUv6x you would do:
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```sh
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make fmu-v6x_default boardconfig
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```
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And then enable the app in the _boardconfig_ UI as shown:
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```txt
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examples --->
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[x] PX4 Simple app ----
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```
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:::info
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Examples are opt-in and not included in firmware by default (although they are in SITL).
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You must explicitly enable them as shown above.
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:::
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보드별 명령어를 사용하여, 예제를 빌드합니다.
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- Gazebo Simulator: `make px4_sitl gz_x500`
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- Pixhawk 6X: `make px4_fmu-v6x_default`
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- Other boards: [Building the Code](../dev_setup/building_px4.md)
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## 앱 테스트(하드웨어)
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### 보드에 펌웨어 업로드합니다.
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업로더를 활성화한 다음 보드를 재설정합니다.
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- Pixhawk 6X: `make px4_fmu-v6x_default upload`
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보드 재설정전에 컴파일 메시지를 인쇄하고 마지막에 다음을 인쇄합니다.
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```sh
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Loaded firmware for X,X, waiting for the bootloader...
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```
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보드가 재설정되고 업로드되면 다음이 인쇄됩니다.
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```sh
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Erase : [====================] 100.0%
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Program: [====================] 100.0%
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Verify : [====================] 100.0%
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Rebooting.
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[100%] Built target upload
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```
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### 콘솔을 연결합니다.
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Now connect to the [system console](../debug/system_console.md) either via serial or USB.
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Hitting **ENTER** will bring up the shell prompt:
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```sh
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nsh>
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```
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'help'을 입력하고 Enter 키를 입력합니다.
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```sh
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nsh> help
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help usage: help [-v] [<cmd>]
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[ df kill mkfifo ps sleep
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? echo losetup mkrd pwd test
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cat exec ls mh rm umount
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cd exit mb mount rmdir unset
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cp free mkdir mv set usleep
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dd help mkfatfs mw sh xd
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Builtin Apps:
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reboot
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perf
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top
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..
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px4_simple_app
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..
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sercon
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serdis
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```
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Note that `px4_simple_app` is now part of the available commands.
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Start it by typing `px4_simple_app` and ENTER:
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```sh
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nsh> px4_simple_app
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Hello Sky!
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```
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이제 어플리케이션이 시스템에 올바르게 등록되었으며, 실제 작업을 수행하도록 확장할 수 있습니다.
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## 앱 테스트(SITL)
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If you're using SITL the _PX4 console_ is automatically started (see [Building the Code > First Build (Using a Simulator)](../dev_setup/building_px4.md#first-build-using-a-simulator)).
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As with the _nsh console_ (see previous section) you can type `help` to see the list of built-in apps.
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Enter `px4_simple_app` to run the minimal app.
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```sh
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pxh> px4_simple_app
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INFO [px4_simple_app] Hello Sky!
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```
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이제 응용 프로그램을 확장할 수 있습니다.
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## 센서 데이터 읽기
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유용한 작업을 수행하려면, 애플리케이션이 입력을 구독하고 출력(예: 모터 또는 서보 명령)을 게시해야 합니다.
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:::tip
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The benefits of the PX4 hardware abstraction comes into play here!
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센서 드라이버와 어떤 식으로든 상호 작용할 필요가 없으며, 보드 또는 센서가 업데이트된 경우 앱을 업데이트할 필요도 없습니다.
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:::
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Individual message channels between applications are called [topics](../middleware/uorb.md). For this tutorial, we are interested in the [VehicleAcceleration](https://github.com/PX4/PX4-Autopilot/blob/main/msg/versioned/VehicleAcceleration.msg) topic, which holds the filtered vehicle acceleration data.
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주제 구독은 간단합니다.
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```cpp
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#include <uORB/topics/vehicle_acceleration.h>
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..
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int sensor_sub_fd = orb_subscribe(ORB_ID(vehicle_acceleration));
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```
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The `sensor_sub_fd` is a topic handle and can be used to very efficiently perform a blocking wait for new data.
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현재 스레드는 절전 모드로 전환되고, 새 데이터를 사용할 수 있게 되면 스케줄러에 의해 자동으로 깨어나며 기다리는 동안 CPU 주기를 소비하지 않습니다.
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To do this, we use the [poll()](https://pubs.opengroup.org/onlinepubs/007908799/xsh/poll.html) POSIX system call.
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Adding `poll()` to the subscription looks like (_pseudocode, look for the full implementation below_):
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```cpp
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#include <poll.h>
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#include <uORB/topics/vehicle_acceleration.h>
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..
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int sensor_sub_fd = orb_subscribe(ORB_ID(vehicle_acceleration));
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/* one could wait for multiple topics with this technique, just using one here */
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px4_pollfd_struct_t fds[] = {
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{ .fd = sensor_sub_fd, .events = POLLIN },
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};
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while (true) {
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/* wait for sensor update of 1 file descriptor for 1000 ms (1 second) */
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int poll_ret = px4_poll(fds, 1, 1000);
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..
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if (fds[0].revents & POLLIN) {
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/* obtained data for the first file descriptor */
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struct vehicle_acceleration_s accel;
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/* copy sensors raw data into local buffer */
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orb_copy(ORB_ID(vehicle_acceleration), sensor_sub_fd, &accel);
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PX4_INFO("Accelerometer:\t%8.4f\t%8.4f\t%8.4f",
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(double)accel.xyz[0],
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(double)accel.xyz[1],
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(double)accel.xyz[2]);
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}
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}
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```
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아래의 명령어로 앱을 다시 컴파일합니다.
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```sh
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make px4_sitl_default
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```
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### uORB 구독 테스트
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마지막 단계는 nsh 셸에 다음을 입력하여 애플리케이션을 백그라운드 프로세스/작업으로 시작하는 것입니다.
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```sh
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px4_simple_app &
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```
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앱은 콘솔에 5개의 센서 값을 출력후 종료합니다.
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```sh
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[px4_simple_app] Accelerometer: 0.0483 0.0821 0.0332
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[px4_simple_app] Accelerometer: 0.0486 0.0820 0.0336
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[px4_simple_app] Accelerometer: 0.0487 0.0819 0.0327
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[px4_simple_app] Accelerometer: 0.0482 0.0818 0.0323
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[px4_simple_app] Accelerometer: 0.0482 0.0827 0.0331
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[px4_simple_app] Accelerometer: 0.0489 0.0804 0.0328
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```
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:::tip
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The [Module Template for Full Applications](../modules/module_template.md) can be used to write background process that can be controlled from the command line.
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:::
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## 데이터 게시
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To use the calculated outputs, the next step is to _publish_ the results.
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아래에서는 태도 주제를 게시하는 방법을 설명합니다.
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:::info
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We've chosen `attitude` because we know that the _mavlink_ app forwards it to the ground control station - providing an easy way to look at the results.
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:::
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The interface is pretty simple: initialize the `struct` of the topic to be published and advertise the topic:
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```c
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#include <uORB/topics/vehicle_attitude.h>
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..
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/* advertise attitude topic */
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struct vehicle_attitude_s att;
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memset(&att, 0, sizeof(att));
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orb_advert_t att_pub_fd = orb_advertise(ORB_ID(vehicle_attitude), &att);
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```
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메인 루프에서 정보가 준비시마다 게시합니다.
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```c
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orb_publish(ORB_ID(vehicle_attitude), att_pub_fd, &att);
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```
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## 전체 예제 코드
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The [complete example code](https://github.com/PX4/PX4-Autopilot/blob/main/src/examples/px4_simple_app/px4_simple_app.c) is now:
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```c
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/****************************************************************************
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*
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* Copyright (c) 2012-2026 PX4 Development Team. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name PX4 nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/**
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* @file px4_simple_app.c
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* Minimal application example for PX4 autopilot
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*
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* @author Example User <mail@example.com>
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*/
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#include <px4_platform_common/px4_config.h>
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#include <px4_platform_common/log.h>
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#include <px4_platform_common/tasks.h>
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#include <px4_platform_common/posix.h>
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#include <unistd.h>
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#include <stdio.h>
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#include <poll.h>
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#include <string.h>
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#include <math.h>
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#include <uORB/uORB.h>
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#include <uORB/topics/vehicle_acceleration.h>
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#include <uORB/topics/vehicle_attitude.h>
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__EXPORT int px4_simple_app_main(int argc, char *argv[]);
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int px4_simple_app_main(int argc, char *argv[])
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{
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PX4_INFO("Hello Sky!");
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/* subscribe to vehicle_acceleration topic */
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int sensor_sub_fd = orb_subscribe(ORB_ID(vehicle_acceleration));
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/* limit the update rate to 5 Hz */
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orb_set_interval(sensor_sub_fd, 200);
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/* advertise attitude topic */
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struct vehicle_attitude_s att;
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memset(&att, 0, sizeof(att));
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orb_advert_t att_pub = orb_advertise(ORB_ID(vehicle_attitude), &att);
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/* one could wait for multiple topics with this technique, just using one here */
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px4_pollfd_struct_t fds[] = {
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{ .fd = sensor_sub_fd, .events = POLLIN },
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/* there could be more file descriptors here, in the form like:
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* { .fd = other_sub_fd, .events = POLLIN },
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*/
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};
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int error_counter = 0;
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for (int i = 0; i < 5; i++) {
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/* wait for sensor update of 1 file descriptor for 1000 ms (1 second) */
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int poll_ret = px4_poll(fds, 1, 1000);
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/* handle the poll result */
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if (poll_ret == 0) {
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/* this means none of our providers is giving us data */
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PX4_ERR("Got no data within a second");
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} else if (poll_ret < 0) {
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/* this is seriously bad - should be an emergency */
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if (error_counter < 10 || error_counter % 50 == 0) {
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/* use a counter to prevent flooding (and slowing us down) */
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PX4_ERR("ERROR return value from poll(): %d", poll_ret);
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}
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error_counter++;
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} else {
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if (fds[0].revents & POLLIN) {
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/* obtained data for the first file descriptor */
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struct vehicle_acceleration_s accel;
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/* copy sensors raw data into local buffer */
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orb_copy(ORB_ID(vehicle_acceleration), sensor_sub_fd, &accel);
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PX4_INFO("Accelerometer:\t%8.4f\t%8.4f\t%8.4f",
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(double)accel.xyz[0],
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(double)accel.xyz[1],
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(double)accel.xyz[2]);
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/* set att and publish this information for other apps
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the following does not have any meaning, it's just an example
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*/
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att.q[0] = accel.xyz[0];
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att.q[1] = accel.xyz[1];
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att.q[2] = accel.xyz[2];
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orb_publish(ORB_ID(vehicle_attitude), att_pub, &att);
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}
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/* there could be more file descriptors here, in the form like:
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* if (fds[1..n].revents & POLLIN) {}
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*/
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}
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}
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PX4_INFO("exiting");
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return 0;
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}
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```
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## 전체 예제 실행
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마지막으로 앱을 실행합니다.
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```sh
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px4_simple_app
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```
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If you start _QGroundControl_, you can check the sensor values in the real time plot ([Analyze > MAVLink Inspector](https://docs.qgroundcontrol.com/master/en/qgc-user-guide/analyze_view/mavlink_inspector.html)).
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## 마무리
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이 튜토리얼에서는 PX4 자동조종장치를 앱 개발에 필요한 내용들을 설명하였습니다.
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Keep in mind that the full list of uORB messages/topics is [available here](https://github.com/PX4/PX4-Autopilot/tree/main/msg/) and that the headers are well documented and serve as reference.
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Further information and troubleshooting/common pitfalls can be found here: [uORB](../middleware/uorb.md).
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다음 페이지에서는 시작 및 중지 기능이 있는 전체 애플리케이션을 작성하기 위한 템플릿을 제공합니다.
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